The NYPD said it is monitoring the situation in Toronto after local police there reported a white van hit a number of pedestrians on a suburban street Monday.
Police said 10 people were killed and another 15 were injured after the rented van jumped a curb Monday afternoon, according to authorities in Toronto. The van's driver left the scene and was later arrested in a confrontation.
The NYPD's verified counter-terrorism account tweeted Monday afternoon it was monitoring the incident, which is standard messaging in such situations and does not indicate an elevated threat for New York City.
“At this point in time, there is no known nexus to New York City," the NYPD said.
Several U.S. law enforcement officials, from different agencies, said the man arrested is Alek Minassian, 25.
Yuen said police were still interviewing witnesses and examining surveillance video of the incident as part of what he called a "complex" investigation.
"I can assure the public all our available resources have been brought in to investigate this tragic situation," he said.
Multiple U.S. and Canadian law enforcement officials briefed on the investigation told NBC News that mental illness was the leading theory based on the preliminary investigation into the incident.
The incident occurred as Cabinet ministers from the major industrial countries were gathered in Canada to discuss a range of international issues in the run-up to the G7 meeting near Quebec City in June.
Video shown on several Canadian outlets showed police arresting the driver, dressed in dark clothes, after officers surrounded him several blocks from where the incident occurred in north Toronto.
Prime Minister Justin Trudeau expressed his sympathies for those involved. "Our hearts go out to everyone affected," Trudeau said in Ottawa. "We are going to have more to learn and more to say in the coming hours."